Programmable baseband filters supporting auto-calibration for a mobile digital cellular television environment

ABSTRACT

A method for processing wireless information is disclosed and may include performing by one or more circuits within a single-chip multi-band RF receiver, the one or more circuits comprising a filter, generating at least one control signal based on a signal strength of a baseband frequency signal generated by the one or more circuits within the single-chip multi-band RF receiver. A bandwidth of the filter may be adjusted using the generated at least one control signal. The generated baseband frequency signal may be filtered utilizing the bandwidth adjusted filter. A frequency response signal of the filter may be determined using a reference frequency signal. An attenuated reference frequency signal may be generated by attenuating the reference frequency signal. The attenuated reference frequency signal may be compared with the frequency response signal. The at least one control signal may be generated based on the comparison.

CROSS-REFERENCE TO RELATED APPLICATIONS/INCORPORATION BY REFERENCE

This application makes reference to, claims priority to, and claims thebenefit of:

U.S. Provisional Application Ser. No. 60/717,915, filed on Sep. 16,2005; andU.S. Provisional Application Ser. No. 60/778,232, filed on Mar. 2, 2006.

This application also makes reference to:

U.S. application Ser. No. ______ (Attorney Docket No. 17373US02) filedon even date herewith;U.S. application Ser. No. ______ (Attorney Docket No. 17374US02) filedon even date herewith;U.S. application Ser. No. ______ (Attorney Docket No. 17376US02) filedon even date herewith;U.S. application Ser. No. ______ (Attorney Docket No. 17377US02) filedon even date herewith; andU.S. application Ser. No. ______ (Attorney Docket No. 17378US02) filedon even date herewith.

Each of the above stated applications is hereby incorporated herein byreference in its entirety.

FIELD OF THE INVENTION

Certain embodiments of the invention relate to on-chip RF tuners. Morespecifically, certain embodiments of the invention relate toprogrammable baseband filters supporting auto-calibration for a mobiledigital cellular television environment.

BACKGROUND OF THE INVENTION

Broadcasting and telecommunications have historically occupied separatefields. In the past, broadcasting was largely an “over-the-air” mediumwhile wired media carried telecommunications. That distinction may nolonger apply as both broadcasting and telecommunications may bedelivered over either wired or wireless media. Present development mayadapt broadcasting to mobility services. One limitation has been thatbroadcasting may often require high bit rate data transmission at rateshigher than could be supported by existing mobile communicationsnetworks. However, with emerging developments in wireless communicationstechnology, even this obstacle may be overcome.

Terrestrial television and radio broadcast networks have made use ofhigh power transmitters covering broad service areas, which enableone-way distribution of content to user equipment such as televisionsand radios. By contrast, wireless telecommunications networks have madeuse of low power transmitters, which have covered relatively small areasknown as “cells”. Unlike broadcast networks, wireless networks may beadapted to provide two-way interactive services between users of userequipment such as telephones and computer equipment.

The introduction of cellular communications systems in the late 1970'sand early 1980's represented a significant advance in mobilecommunications. The networks of this period may be commonly known asfirst generation, or “1G” systems. These systems were based upon analog,circuit-switching technology, the most prominent of these systems mayhave been the advanced mobile phone system (AMPS). Second generation, or“2G” systems, ushered improvements in performance over 1G systems andintroduced digital technology to mobile communications. Exemplary 2Gsystems include the global system for mobile communications (GSM),digital AMPS (D-AMPS), and code division multiple access (CDMA). Many ofthese systems have been designed according to the paradigm of thetraditional telephony architecture, often focused on circuit-switchedservices, voice traffic, and supported data transfer rates up to 14.4kbits/s. Higher data rates were achieved through the deployment of“2.5G” networks, many of which were adapted to existing 2G networkinfrastructures. The 2.5G networks began the introduction ofpacket-switching technology in wireless networks. However, it is theevolution of third generation, or “3G” technology that may introducefully packet-switched networks, which support high-speed datacommunications.

Standards for digital television terrestrial broadcasting (DTTB) haveevolved around the world with different systems being adopted indifferent regions. The three leading DTTB systems are, the advancedstandards technical committee (ATSC) system, the digital video broadcastterrestrial (DVB-T) system, and the integrated service digitalbroadcasting terrestrial (ISDB-T) system. The ATSC system has largelybeen adopted in North America, South America, Taiwan, and South Korea.This system adapts trellis coding and 8-level vestigial sideband (8-VSB)modulation. The DVB-T system has largely been adopted in Europe, theMiddle East, Australia, as well as parts of Africa and parts of Asia.The DVB-T system adapts coded orthogonal frequency division multiplexing(COFDM). The OFDM spread spectrum technique may be utilized todistribute information over many carriers that are spaced apart atspecified frequencies. The OFDM technique may also be referred to asmulti-carrier or discrete multi-tone modulation. This technique mayresult in spectral efficiency and lower multi-path distortion, forexample. The ISDB-T system has been adopted in Japan and adaptsbandwidth segmented transmission orthogonal frequency divisionmultiplexing (BST-OFDM). The various DTTB systems may differ inimportant aspects; some systems employ a 6 MHz channel separation, whileothers may employ 7 MHz or 8 MHz channel separations.

While 3G systems are evolving to provide integrated voice, multimedia,and data services to mobile user equipment, there may be compellingreasons for adapting DTTB systems for this purpose. One of the morenotable reasons may be the high data rates that may be supported in DTTBsystems. For example, DVB-T may support data rates of 15 Mbits/s in an 8MHz channel in a wide area single frequency network (SFN). There arealso significant challenges in deploying broadcast services to mobileuser equipment. Because of form factor constraints, many handheldportable devices, for example, may require that PCB area be minimizedand that services consume minimum power to extend battery life to alevel that may be acceptable to users. Another consideration is theDoppler Effect in moving user equipment, which may cause inter-symbolinterference in received signals. Among the three major DTTB systems,ISDB-T was originally designed to support broadcast services to mobileuser equipment. While DVB-T may not have been originally designed tosupport mobility broadcast services, a number of adaptations have beenmade to provide support for mobile broadcast capability. The adaptationof DVB-T to mobile broadcasting is commonly known as DVB handheld(DVB-H). The broadcasting frequencies for Europe are in UHF (bands IV/V)and in the US, the 1670-1675 MHz band that has been allocated for DVB-Hoperation. Additional spectrum is expected to be allocated in the L-bandworld-wide.

To meet requirements for mobile broadcasting the DVB-H specificationsupports time slicing to reduce power consumption at the user equipment,addition of a 4K mode to enable network operators to make tradeoffsbetween the advantages of the 2K mode and those of the 8K mode, and anadditional level of forward error correction on multi-protocolencapsulated data—forward error correction (MPE-FEC) to make DVB-Htransmissions more robust to the challenges presented by mobilereception of signals and to potential limitations in antenna designs forhandheld user equipment. DVB-H may also use the DVB-T modulationschemes, like QPSK and 16-quadrature amplitude modulation (16-QAM).

While several adaptations have been made to provide support for mobilebroadcast capabilities in DVB-T, concerns regarding device size, cost,and/or power requirements still remain significant constraints for theimplementation of handheld portable devices enabled for digital videobroadcasting operations. For example, typical DVB-T tuners or receiversin mobile terminals may employ super-heterodyne architectures with oneor two intermediate frequency (IF) stages and direct sampling of thepassband signal for digital quadrature down-conversion. Moreover,external tracking and SAW filters may generally be utilized for channelselection and image rejection. Such approaches may result in increasedpower consumption and high external component count, which may limittheir application in handheld portable devices. As a result, the successof mobile broadcast capability of DVB-T may depend in part on theability to develop TV tuners that have smaller form factor, are producedat lower cost, and consume less power during operation. Furthermore,process and temperature variations within conventional tuners orreceivers in mobile terminals result in deviation of the frequencyresponse of analog filters used within the tuners or receivers. Suchdeviation of the frequency response results in deterioration of channelselection capabilities of the tuners or receivers.

Further limitations and disadvantages of conventional and traditionalapproaches will become apparent to one of skill in the art, throughcomparison of such systems with some aspects of the present invention asset forth in the remainder of the present application with reference tothe drawings.

BRIEF SUMMARY OF THE INVENTION

A system and/or method is provided for programmable baseband filterssupporting auto-calibration for a mobile digital cellular televisionenvironment, substantially as shown in and/or described in connectionwith at least one of the figures, as set forth more completely in theclaims.

These and other advantages, aspects and novel features of the presentinvention, as well as details of an illustrated embodiment thereof, willbe more fully understood from the following description and drawings.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

FIG. 1A is a block diagram illustrating an exemplary mobile terminal, inaccordance with an embodiment of the invention.

FIG. 1B is a block diagram illustrating exemplary communication betweena dual-band RF receiver and a digital baseband processor in a mobileterminal, in accordance with an embodiment of the invention.

FIG. 1C is a block diagram illustrating an exemplary single-chipdual-band RF receiver with an integrated LNA in each front-end, inaccordance with an embodiment of the invention.

FIG. 2A is a block diagram of an exemplary analog baseband processingblock supporting auto-calibration, in accordance with an embodiment ofthe invention.

FIG. 2B is a schematic diagram of an exemplary baseband filter that maybe used in accordance with an embodiment of the invention.

FIG. 2C is a block diagram of an exemplary baseband processing blockusing programmable analog (Chebyschev) filters and an auto-calibrationloop, in accordance with an embodiment of the invention.

FIG. 2D is a flow diagram illustrating exemplary steps in the operationof a filter supporting auto-calibration mode, in accordance with anembodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Certain embodiments of the invention may be found in a method and systemfor programmable baseband filters supporting auto-calibration for amobile digital cellular television environment. Aspects of the methodmay comprise generating within a single-chip multi-band RF receiver, atleast one control signal based on signal strength of a basebandfrequency signal generated within the single-chip multi-band RFreceiver. A bandwidth of a filter integrated within the single-chipmulti-band RF receiver may be adjusted via the generated at least onecontrol signal. The filter may be used for filtering the generatedbaseband frequency signal. A frequency response signal of the filterintegrated within the single-chip multi-band RF receiver may bedetermined via a reference frequency signal. An attenuated referencefrequency signal may be generated by attenuating the reference frequencysignal. The attenuated reference frequency signal may be compared withthe frequency response signal.

The control signal may be generated based on the comparison of theattenuated reference frequency and the frequency response signal. Theattenuated reference frequency signal and the frequency response signalmay be averaged prior to the comparing. The filter integrated within thesingle-chip multi-band RF receiver may comprise a low-pass filter, suchas a Chebyschev filter. A capacitance of the filter integrated withinthe single-chip multi-band RF receiver may be adjusted based on thegenerated at least one control signal. A cut-off frequency of the filterintegrated within the single-chip multi-band RF receiver may be adjustedvia the generated at least one control signal. For example, the cut-offfrequency of the filter integrated within the single-chip multi-band RFreceiver may be adjusted within the range of about 2 MHz to about 5 MHz.

FIG. 1A is a block diagram illustrating an exemplary mobile terminal, inaccordance with an embodiment of the invention. Referring to FIG. 1A,there is shown a mobile terminal 120 that may comprise an RF receiver123 a, an RF transmitter 123 b, a digital baseband processor 129, aprocessor 125, and a memory 127. A receive antenna 121 a may becommunicatively coupled to the RF receiver 123 a. A transmit antenna 121b may be communicatively coupled to the RF transmitter 123 b. The mobileterminal 120 may be operated in a system, such as the cellular networkand/or digital video broadcast network described in FIG. 1A, forexample.

The RF receiver 123 a may comprise suitable logic, circuitry, and/orcode that may enable processing of received RF signals. The RF receiver123 a may enable receiving RF signals in a plurality of frequency bands.For example, the RF receiver 123 a may enable receiving DVB-Htransmission signals via the UHF band, from about 470 MHz to about 890MHz, the 1670-1675 MHz band, and/or the L-band, from about 1400 MHz toabout 1700 MHz, for example. Moreover, the RF receiver 123 a may enablereceiving signals in cellular frequency bands, for example. Eachfrequency band supported by the RF receiver 123 a may have acorresponding front-end circuit for handling low noise amplification anddown conversion operations, for example. In this regard, the RF receiver123 a may be referred to as a multi-band receiver when it supports morethan one frequency band. In another embodiment of the invention, themobile terminal 120 may comprise more than one RF receiver 123 a,wherein each of the RF receivers 123 a may be a single-band or amulti-band receiver.

The RF receiver 123 a may quadrature down convert the received RF signalto a baseband frequency signal that comprises an in-phase (I) componentand a quadrature (Q) component. The RF receiver 123 a may perform directdown conversion of the received RF signal to a baseband frequencysignal, for example. In some instances, the RF receiver 123 a may enableanalog-to-digital conversion of the baseband signal components beforetransferring the components to the digital baseband processor 129. Inother instances, the RF receiver 123 a may transfer the baseband signalcomponents in analog form.

The digital baseband processor 129 may comprise suitable logic,circuitry, and/or code that may enable processing and/or handling ofbaseband frequency signals. In this regard, the digital basebandprocessor 129 may process or handle signals received from the RFreceiver 123 a and/or signals to be transferred to the RF transmitter123 b, when the RF transmitter 123 b is present, for transmission to thenetwork. The digital baseband processor 129 may also provide controland/or feedback information to the RF receiver 123 a and to the RFtransmitter 123 b based on information from the processed signals. Thedigital baseband processor 129 may communicate information and/or datafrom the processed signals to the processor 125 and/or to the memory127. Moreover, the digital baseband processor 129 may receiveinformation from the processor 125 and/or to the memory 127, which maybe processed and transferred to the RF transmitter 123 b fortransmission to the network.

The RF transmitter 123 b may comprise suitable logic, circuitry, and/orcode that may enable processing of RF signals for transmission. The RFtransmitter 123 b may enable transmission of RF signals in a pluralityof frequency bands. Moreover, the RF transmitter 123 b may enabletransmitting signals in cellular frequency bands, for example. Eachfrequency band supported by the RF transmitter 123 b may have acorresponding front-end circuit for handling amplification and upconversion operations, for example. In this regard, the RF transmitter123 b may be referred to as a multi-band transmitter when it supportsmore than one frequency band. In another embodiment of the invention,the mobile terminal 120 may comprise more than one RF transmitter 123 b,wherein each of the RF transmitters 123 b may be a single-band or amulti-band transmitter.

The RF transmitter 123 b may quadrature up convert the basebandfrequency signal comprising I/Q components to an RF signal. The RFtransmitter 123 b may perform direct up conversion of the basebandfrequency signal to a baseband frequency signal, for example. In someinstances, the RF transmitter 123 b may enable digital-to-analogconversion of the baseband signal components received from the digitalbaseband processor 129 before up conversion. In other instances, the RFtransmitter 123 b may receive baseband signal components in analog form.

The processor 125 may comprise suitable logic, circuitry, and/or codethat may enable control and/or data processing operations for the mobileterminal 120. The processor 125 may be utilized to control at least aportion of the RF receiver 123 a, the RF transmitter 123 b, the digitalbaseband processor 129, and/or the memory 127. In this regard, theprocessor 125 may generate at least one signal for controllingoperations within the mobile terminal 120. The processor 125 may alsoenable executing of applications that may be utilized by the mobileterminal 120. For example, the processor 125 may execute applicationsthat may enable displaying and/or interacting with content received viaDVB-H transmission signals in the mobile terminal 120.

The memory 127 may comprise suitable logic, circuitry, and/or code thatmay enable storage of data and/or other information utilized by themobile terminal 120. For example, the memory 127 may be utilized forstoring processed data generated by the digital baseband processor 129and/or the processor 125. The memory 127 may also be utilized to storeinformation, such as configuration information, that may be utilized tocontrol the operation of at least one block in the mobile terminal 120.For example, the memory 127 may comprise information necessary toconfigure the RF receiver 123 a to enable receiving DVB-H transmissionin the appropriate frequency band.

FIG. 1B is a block diagram illustrating exemplary communication betweena dual-band RF receiver and a digital baseband processor in a mobileterminal, in accordance with an embodiment of the invention. Referringto FIG. 1B, there is shown a dual-band RF receiver 130, ananalog-to-digital converter (ADC) 134, and a digital baseband processor132. The dual-band RF receiver 130 may comprise a UHF front-end 131 a,an L-band front-end 131 b, a baseband block 133 a, a received signalstrength indicator (RSSI) block 133 b, and a synthesizer 133 c. Thedual-band RF receiver 130, the analog-to-digital converter (ADC) 134,and/or the digital baseband processor 132 may be part of a mobileterminal, such as the mobile terminal 120 in FIG. 1A, for example.

The dual-band RF receiver 130 may comprise suitable logic, circuitry,and/or code that may enable handling of UHF and L-band signals. Thedual-band RF receiver 130 may be enabled via an enable signal, such asthe signal RxEN 139 a, for example. In this regard, enabling thedual-band RF receiver 130 via the signal RxEN 139 a by a 1:10 ON/OFFratio may allow time slicing in DVB-H while reducing power consumption.At least a portion of the circuitry within the dual-band RF receiver 130may be controlled via the control interface 139 b. The control interface139 b may receive information from, for example, a processor, such asthe processor 125 in FIG. 1A, or from the digital baseband processor132. The control interface 139 b may comprise more than one bit. Forexample, when implemented as a 2-bit interface, the control interface139 a may be an inter-integrated circuit (I2C) interface.

The UHF front-end 131 a may comprise suitable logic, circuitry, and/orcode that may enable low noise amplification and direct down conversionof UHF signals. In this regard, the UHF front-end 131 a may utilize anintegrated low noise amplifier (LNA) and mixers, such as passive mixers,for example. The UHF front-end 131 a may communicate the resultingbaseband frequency signals to the baseband block 133 a for furtherprocessing.

The L-band front-end 131 b may comprise suitable logic, circuitry,and/or code that may enable low noise amplification and direct downconversion of L-band signals. In this regard, the L-band front-end 131 bmay utilize an integrated LNA and mixers, such as passive mixers, forexample. The L-band front-end 131 b may communicate the resultingbaseband frequency signals to the baseband block 133 a for furtherprocessing. The dual-band RF receiver 130 may enable one of the UHFfront-end 131 a and the L-band front-end 131 b based on currentcommunication conditions.

The synthesizer 133 c may comprise suitable logic, circuitry, and/orcode that may enable generating the appropriate local oscillator (LO)signal for performing direct down conversion in either the UHF front-end131 a or the L-band front-end 131 b. Since the synthesizer 133 c mayenable fractional division of a source frequency when generating the LOsignal, a large range of crystal oscillators may be utilized as afrequency source for the synthesizer 133 c. This approach may enable theuse of an existing crystal oscillator in a mobile terminal PCB, thusreducing the number of external components necessary to support theoperations of the dual-band RF receiver 130, for example. Thesynthesizer 133 may generate a common LO signal for the UHF front-end131 a and for the L-band front-end 131 b. In this regard, the UHFfront-end 131 a and the L-band front-end 131 b may enable dividing theLO signal in order to generate the appropriate signal to perform downconversion from the UHF band and from the L-band respectively. In someinstances, the synthesizer 133 may have at least one integrated voltagecontrolled oscillator (VCO) for generating the LO signal. In otherinstances, the VCO may be implemented outside the synthesizer 133.

The baseband block 133 a may comprise suitable logic, circuitry, and/orcode that may enable processing of I/Q components generated from thedirect down conversion operations in the UHF front-end 131 a and theL-band front-end 131 b. The baseband block 133 a may enableamplification and/or filtering of the I/Q components in analog form. Thebaseband block 133 a may communicate the processed I component, that is,signal 135 a, and the processed Q component, that is, signal 135 c, tothe ADC 134 for digital conversion.

The RSSI block 133 b may comprise suitable logic, circuitry, and/or codethat may enable measuring the strength, that is, the RSSI value, of areceived RF signal, whether UHF or L-band signal. The RSSI measurementmay be performed, for example, after the received RF signal is amplifiedin either the UHF front-end 131 a or the L-band front-end 131 b. TheRSSI block 133 b may communicate the analog RSSI measurement that is,signal 135 e, to the ADC 134 for digital conversion.

The ADC 134 may comprise suitable logic, circuitry, and/or code that mayenable digital conversion of signals 135 a, 135 c, and/or 135 e tosignals 135 b, 135 d, and/or 135 f respectively. In some instances, theADC 134 may be integrated into the dual-band RF receiver 130 or into thedigital baseband processor 132.

The digital baseband processor 132 may comprise suitable logic,circuitry, and/or code that may enable processing and/or handling ofbaseband frequency signals. In this regard, the digital basebandprocessor 132 may be the same or substantially similar to the digitalbaseband processor 129 described in FIG. 1A. The digital basebandprocessor 132 may enable generating at least one signal, such as thesignals AGC_BB 137 a and AGC_RF 137 b, for adjusting the operations ofthe dual-band RF receiver 130. For example, the signal AGC_BB 137 a maybe utilized to adjust the gain provided by the baseband block 133 a onthe baseband frequency signals generated from either the UHF front-end131 a or the L-band front-end 131 b. In another example, the signalAGC_RF 137 b may be utilized to adjust the gain provided by anintegrated LNA in either the UHF front-end 131 a or the L-band front-end131 b. In another example, the digital baseband processor 132 maygenerate at least one control signal or control information communicatedto the dual-band RF receiver 130 via the control interface 139 b foradjusting operations within the dual-band RF receiver 130.

FIG. 1C is a block diagram illustrating an exemplary single-chipdual-band RF receiver with an integrated LNA in each front-end, inaccordance with an embodiment of the invention. Referring to FIG. 1C,there is shown a single-chip dual-band RF receiver 140 a that maycomprise a UHF front-end 148 a, an L-band front-end 148 b, a basebandblock 164, a logarithmic amplifier (logarithmic amplifier) 172, a Σ-Δfractional-N synthesizer 174, a VCO block 176, a digital interface 160,an ADC 162, an oscillator 180, and a buffer 182.

The single-chip dual-band RF receiver 140 a may be fabricated using anyof a plurality of semiconductor manufacturing processes, for example,complimentary metal-oxide-semiconductor (CMOS) processes, bipolar CMOS(BiCMOS), or Silicon Germanium (SiGe). The single-chip dual-band RFreceiver 140 a may be implemented using differential structures tominimize noise effects and/or substrate coupling, for example. Thesingle-chip dual-band RF receiver 140 a may utilize low drop out (LDO)voltage regulators to regulate and clean up on-chip voltage supplies. Inthis regard, the LDO voltage regulators may be utilized to transformexternal voltage sources to the appropriate on-chip voltages.

When the single-chip dual-band RF receiver 140 a is implementedutilizing a CMOS process, some design considerations may includeachieving low noise figure (NF) values, wide-band operation, highsignal-to-noise ration (SNR), performing DC offset removal, achievinghigh input second-order and third-order intercept points (IIP2 andIIP3), and/or reducing I/Q mismatch, for example.

The single-chip dual-band RF receiver 140 a may receive UHF signals viaa first antenna 142 a, a UHF filter 144 a, and a first balum 146 a. TheUHF filter 144 a enables band pass filtering, wherein the band pass maybe about 470 to about 702 MHz for cellular signals, for example, orabout 470 to about 862 MHz, for other types of received signals, forexample. The balum 146 a enables balancing the filtered signals beforebeing communicated to the UHF front-end 148 a.

The single-chip dual-band RF receiver 140 a may receive L-band signalsvia a second antenna 142 b, an L-band filter 144 b, and a second balum146 b. The L-band filter 144 b enables band pass filtering, wherein theband pass may be about 1670 to about 1675 MHz for signals in US systems,for example, or about 1450 to about 1490 MHz, for signals in Europeansystems, for example. The balum 146 b enables balancing the filteredsignals before being communicated to the L-band front-end 148 a. In someinstances, antennas 142 a and 142 b may be implemented utilizing asingle antenna communicatively coupled to the single-chip dual-band RFreceiver 140 a that may support receiving radio signals operating in theUHF IV/V and/or L-band, for example.

The UHF front-end 148 a may comprise a variable low noise amplifier(LNA) 150 a, a mixer 152 a, a mixer 154 a, and a LO signal divider 156.The variable LNA 150 a may comprise suitable logic and/or circuitry thatmay enable amplification of the UHF signals received. Matching betweenthe output of the balum 146 a and the input of the variable LNA 150 amay be achieved by utilizing off-chip series inductors, for example. Thevariable LNA 150 a may implement continuous gain control by currentsteering that may be controlled by a replica scheme within the variableLNA 150 a. The gain of the variable LNA 150 a may be adjusted via thesignal AGC_RF 137 b, for example.

The mixers 152 a and 154 a may comprise suitable logic and/or circuitrythat may enable generating in-phase (I) and quadrature (Q) components ofthe baseband frequency signal based on direct down conversion of theamplified received UHF signal with the quadrature signals 186I and 186Qgenerated by the divider block 156. The mixers 152 a and 154 a may bepassive mixers in order to achieve high linearity and/or low flickernoise, for example. The LO signal divider 156 may comprise suitablelogic, circuitry, and/or code that may enable dividing of the LO signal186 by a factor of 2 (:/2) or a factor of 3 (:/3) and at the same timeprovide quadrature outputs 186I and 186Q, wherein 186I and 186Q have 90degrees separation between them. The factor of 3 division may be usedwhen the received UHF signal band is about 470 to about 600 MHz, forexample. The factor of 2 division may be used when the received UHFsignal band is about 600 to about 900 MHz, for example. The I/Qcomponents generated by the mixers 152 a and 154 a may be communicatedto the baseband block 164.

The L-band front-end 148 b may comprise a variable LNA 150 b, a mixer152 a, a mixer 154 a, and a LO signal generator 158. The variable LNA150 a may comprise suitable logic and/or circuitry that may enableamplification of the L-band signals received. Matching between theoutput of the balum 146 b and the input of the variable LNA 150 b may beachieved by utilizing off-chip series inductors, for example. Thevariable LNA 150 b may implement continuous gain control by currentsteering that may be controlled by a replica scheme within the variableLNA 150 b. The gain of the variable LNA 150 b may be adjusted via thesignal AGC_RF 137 b, for example.

The mixers 152 b and 154 b may comprise suitable logic and/or circuitrythat may enable generating I/Q components of the baseband frequencysignal based on the direct down conversion of the amplified receivedL-band signal with the LO signals 1581 and 158Q generated by the LOgenerator block 158. The mixers 152 b and 154 b may be passive mixers inorder to achieve high linearity and/or low flicker noise, for example.The LO signal generator 158 may comprise suitable logic, circuitry,and/or code that may enable generation of quadrature LO signals 1581 and158Q, that is, signals with 90 degree phase split between them, from theLO signal 186. The I/Q components generated by the mixers 152 b and 154b may be communicated to the baseband block 164.

The logarithmic amplifier 172 may comprise suitable logic, circuitry,and/or code that may enable generation of a wideband, received signalstrength indicator (RSSI) signal, such as the signal 135 e, based on theoutput of the variable LNA 150 a. The RSSI signal indicates the totalamount of signal power that is present at the output of the LNA, forexample. The RSSI signal may be utilized by, for example, the digitalbaseband processor 132 in FIG. 1C, to adjust the gain of the variableLNA 150 a in the presence of RF interference to achieve NF and/orlinearity performance that meets blocking and/or intermodulationspecifications, for example. In this regard, interference may refer toblocker signals, for example. Blocker signals may be unwanted signals infrequency channels outside the wanted or desired channel that maydisturb the reception of the wanted signals. This effect may be a resultof blockers generating large signals within the receiver path. Theselarge signals may introduce harmonics, intermodulation products, and/orunwanted mixing products that crosstalk with the wanted signals. Inanother embodiment of the invention, the logarithmic amplifier 172 mayenable generating a wideband, RSSI signal, such as the signal 135 e,based on the output of the variable LNA 150 b. In this instance, theRSSI signal may be utilized by to adjust the gain of the variable LNA150 b.

The baseband block 164 may comprise an in-phase component processingpath and a quadrature component processing path. The in-phase processingpath may comprise at least one programmable gain amplifier (PGA) 166 a,a baseband filter 168 a, and at least one PGA 170 a. The quadraturecomponent processing path may comprise at least one PGA 166 b, abaseband filter 168 b, and at least one PGA 170 b. The PGAs 166 a, 166b, 170 a, and 170 b may comprise suitable logic, circuitry, and/or codethat may enable amplification of the down converted components of thebaseband frequency signal generated by the RF front-end. The gain of thePGAs 166 a, 166 b, 170 a, and 170 b may be digitally programmable. Inaddition, at the output of the PGAs 166 a and 166 b, a programmable polemay be utilized to reduce linearity requirements for the basebandfilters 168 a and 168 b respectively. Since the static and time-varyingDC offset may saturate the operation of the single-chip dual-band RFreceiver 140 a, the PGAs 166 a, 166 b, 170 a, and 170 b may utilize DCservo loops to address DC offset issues. The gain of the PGAs 166 a, 166b, 170 a, and/or 170 b may be controlled via the AGC_BB signal 137 a,for example. In this regard, the ADC 162 may be utilized to providedigital control of the PGAs 166 a, 166 b, 170 a, and/or 170 b when theAGC_BB signal 137 a is an analog signal.

The baseband filters 168 a and 168 b may comprise suitable logic,circuitry, and/or code that may enable channel selection, for example.Channel selection may be performed by filters, such as an N^(th) orderlowpass Chebyschev filter implemented by active integrators in aleapfrog configuration, for example. For the correct tuning of thecharacteristics of the filters, an on-chip auto-calibration loop may beactivated upon power-up. The auto-calibration loop may set up the cornerfrequency to the correct vale required to meet the requirements of thecommunications standard for which the receiver is designed. ForDVB-T/DVB-H, the value f_(o) of the filter response may be set to avalue from 2 to 5 MHz thus supporting the different channel bandwidthsof 5-8 MHz specified by DVB-T/DVB-H standards. During auto-calibration,a tone at the appropriate f_(−3dB) may be generated on-chip and may beapplied at the input of the baseband filters 168 a and 168 b forcomparison with the filter output of a root-mean-squared (RMS) detector.A digitally controlled loop may be utilized to adjust the basebandfilter bandwidth until the output of the baseband filter and the RMSdetector are the same.

The Σ-Δ fractional-N synthesizer 174 may comprise suitable logic,circuitry, and/or code that may enable LO generation that may beindependent of the reference crystal frequency, such as the crystal 178,for example. In this regard, the synthesizer 174 may generate a signal,such as the signal 190, for example, to control the operation of the VCOblock 176 and therefore the generation of the LO signal 186. Since thesynthesizer 174 may enable fractional synthesis, the single-chip dualband RF receiver 140 a may utilize the same crystal utilized by otheroperations in the mobile terminal while maintaining fine tuningcapability. The synthesizer 174 may receive a reference frequency signalfrom the crystal 178 via an oscillator 180, for example. The output ofthe oscillator 180 may also be buffered by the buffer 182 to generate aclock signal 184, for example.

The VCO block 176 may comprise suitable logic, circuitry, and/or codethat may enable generating the LO signal 186 utilized by the UHFfront-end 148 a and the L-band front-end 148 b for direct downconversion of the received RF signals. The VCO block 176 may comprise atleast one VCO, wherein each VCO may have cross-coupled NMOS and PMOSdevices and metal-oxide-semiconductor (MOS) varactors in an accumulationmode for tuning. In this regard, a switched varactor bank may beutilized for providing coarse tuning. The VCO block 176 may provide arange of about 1.2 to about 1.8 GHz when implemented utilizing two VCOs,for example. When more than one VCO is utilized in implementing the VCOblock 176, selecting the proper VCO for generating the LO signal 186 maybe based on the type of RF signal being received by the single-chip dualband RF receiver 140 a.

The digital interface 160 may comprise suitable logic, circuitry, and/orcode that may enable controlling circuitry within the single-chip dualband RF receiver 140 a. The digital interface 160 may comprise aplurality of registers for storing control and/or operationalinformation for use by the single-chip dual-band RF receiver 140 a. Thedigital interface 160 may enable receiving the signal RxEN 139 a thatmay be utilized to perform 1:10 ON/OFF ratio time slicing in DVB-H whilereducing power consumption. Moreover, the digital interface 160 mayenable receiving the control interface 139 b from, for example, aprocessor, such as the processor 125 in FIG. 1A, or from the digitalbaseband processor 132 in FIG. 1C. The control interface 139 b maycomprise more than one bit. The control interface 139 b may be utilizedto control the synthesis operations of the synthesizer 174 and/or thefiltering operations of the baseband filters 168 a and 168 b. Thecontrol interface 139 b may also be utilized to adjust the bias ofcircuits within the single-chip dual-band RF receiver 140 a, such asthose of the variable LNAs 150 a and 150 b, the PGAs 166 a, 166 b, 170a, and 170 b, and/or the baseband filters 168 a and 168 b, for example.

FIG. 2A is a block diagram of an exemplary analog baseband processingblock supporting auto-calibration, in accordance with an embodiment ofthe invention. Referring to FIG. 2A, the baseband processing block 200 amay comprise a plurality of programmable gain amplifiers (PGAs) 204 a,208 a, 210 a, and 214 a, and baseband filters 206 a and 212 a.

For example, the baseband processing block 200 a may comprise anin-phase (I) component processing path comprising PGAs 204 a and 208 a,and a baseband filter 206 a. The in-phase component processing path ofthe baseband processing block 200 a may process an input in-phase (I)signal 216 a to generate an output in-phase signal 218 a. The inputin-phase signal 216 a may comprise a down converted component of abaseband frequency signal generated by an RF front end, for example. Thebaseband processing block 200 a may also comprise a quadrature component(Q) processing path comprising PGAs 210 a and 214 a, and a basebandfilter 212 a. The quadrature component processing path of the basebandprocessing block 200 a may process an input quadrature (Q) signal 220 ato generate an output quadrature signal 222 a. The input quadraturesignal 220 a may comprise a down converted component of a basebandfrequency signal generated by an RF front end, for example.

The PGAs 204 a, 208 a, 210 a, and 214 a may comprise suitable logic,circuitry, and/or code that may enable amplification of the downconverted components of the baseband frequency signals 216 a and 220 a.The PGAs 204 a, 208 a, 210 a, and 214 a may be digitally programmable.For example, at the output of the PGAs 204 a and 210 a, a programmablepole may be utilized to reduce linearity requirements for the basebandfilters 206 a and 212 a, respectively. Furthermore, the PGAs 204 a, 208a, 210 a, and 214 a may utilize DC servo loops to address DC offsetissues. The baseband filters 206 a and 212 a may comprise suitablelogic, circuitry, gain and/or code that may enable channel selection,for example. Channel selection may be performed by a filter bank, suchas an Nth order Chebyschev filter implemented by active integrators, forexample.

FIG. 2B is a schematic diagram of an exemplary baseband filter that maybe used in accordance with an embodiment of the invention. Referring toFIG. 2B, the baseband filter 200 b may comprise a sixth order Chebyschevfilter, for example. The Chebyschev filter 200 b may comprise aplurality of operational amplifiers (opamps) a1, . . . a6, a pluralityof variable capacitors c1, . . . , c6, and a plurality of resistors r1,. . . , r14. In one embodiment of the invention, the opamp integratorsa1-c1-r1 and a6-c6-r8 may be arranged in a leapfrog formation. Each ofthe capacitors c1, . . . , c6 may be implemented as a binary weightedarray of capacitors that may be controlled by 6 bits, for example.

In operation, the cut-off frequency f0 of the Chebyschev filter 200 bmay be changed during channel selection. For example, the cut-offfrequency f0 of the Chebyschev filter 200 b may be set to a value from 2MHz, for example, thereby supporting channel bandwidth of about 5 MHz toabout 8 MHz, which is specified by the DVB-T standard. Even though thebaseband filter 200 b comprises a sixth order Chebyschev filter, thepresent invention may not be so limited and an Nth order low-pass filter(LPF) may be utilized instead.

Even though the baseband filter 200 b is described as a Chebyschevfilter, the present invention may not be so limited. Other types offilters may also be utilized, such as cascaded biquad filters, forexample. Furthermore, even though operational amplifier (opamp)-RCintegrators are utilized within the filter 200 b, the present inventionmay not be so limited and other integrator implementations may also beutilized, such as a Gm-C integrator.

FIG. 2C is a block diagram of an exemplary baseband processing blockusing Chebyschev filters and an auto-calibration loop, in accordancewith an embodiment of the invention. Referring to FIG. 2C, the basebandprocessing block 200 c may comprise a plurality of programmable gainamplifiers (PGAs) 202 c, 204 c, 218 c, and 220 c, and baseband filters210 c and 212 c. In addition, the baseband processing block may comprisean auto-calibration loop circuitry. The auto-calibration loop circuitrymay comprise switches 206 c, 214 c, 208 c, and 216 c, frequencygenerator 222 c, an amplifier 224 c, root-means-square (rms) blocks 226c and 228 c, a comparator 230 c, and control logic block 234 c.

Even though rms blocks are used within the baseband processing block 200c, the present invention may not be so limited and peak detectors may beused instead of the rms blocks.

The functionality of the PGAs 202 c, 218 c, 204 c, and 220 c may besimilar to the functionality of the PGAs 204 a, 208 a, 210 a, and 214 ain FIG. 2A, respectively. Similarly, the functionality of the basebandfilters 210 c and 212 c may be the same as the functionality of thebaseband filters 206 a and 212 a in FIG. 2A, respectively. For example,the baseband filters 210 c and 212 c may each comprise a sixth orderChebyschev filters, such as the Chebyschev filter 211 c or theChebyschev filter 200 b in FIG. 2B.

During an exemplary auto-calibration of the quadrature signal path,switches 208 c and 216 c may be switched to allow signal communicationin the auto-calibration loop path. The frequency signal generator 222 cmay generate a reference frequency signal f−3 dB. The referencefrequency signal may then be applied at the input of the baseband filter212 c and the amplifier 224 c. The amplifier 224 c may attenuate thereference frequency signal by 3 dB, for example. The attenuatedfrequency signal may then be communicated to the rms block 228 c. Afterthe baseband filter 212 c filters the reference frequency signalcommunicated from the frequency signal generator 222 c, the filteredreference frequency signal may be communicated to the rms block 226 c.

Even though the frequency signal generator 222 c generates a referencefrequency signal f−3 dB that corresponds to a cut-off frequency of amain signal attenuated by 3 dB, the present invention may not be solimited. In this regard, the frequency signal generator 222 c maygenerate a reference frequency signal f-xdB that corresponds to acut-off frequency of a main signal attenuated by xdB. In such instances,the amplifier 224 c may attenuate the signal generated by the signalgenerator 222 c by x dB.

The rms blocks 226 c and 228 c may perform an averaging function, forexample, on the filtered reference frequency signal and the attenuatedreference frequency signal, respectively. The averaged filteredreference frequency signal and the attenuated reference frequency signalmay be compared by the comparator 230 c. A comparator output signal maybe communicated from the comparator 230 c to the control logic block 234c. The control logic block 234 c may comprise suitable circuitry, logic,and/or code and may enable generation of a control signal 236 c. Thecontrol logic block 234 c may use a clock signal 232 c during thecontrol signal generation. In one exemplary embodiment of the invention,if a sixth order Chebyschev filter is used within the basebandprocessing block 200 c, the control signal 236 c may comprise a 6-bitsignal. In this regard, six bits may be used to program or adjust thecapacitance of each variable capacitor c1, . . . , c6 in the filter 211c.

The control signal 236 c may be communicated to each of the basebandfilters 210 c and 212 c. The baseband filters 210 c and 212 c may adjustcapacitance of the variable capacitors within the filters and, thereby,change the cut-off frequency and the filter bandwidth. The cut-offfrequency and filter bandwidth of the filters 210 c and 212 c may beadjusted until attenuation of the reference frequency signal by thefilter 212 c equals 3 dB, for example.

Even though an auto-calibration loop is described with respect to thequadrature signal path of the baseband processing block 200 c, the sameauto-calibration loop circuitry, such as the reference frequencygenerator 222 c, amplifier 224 c, rms blocks 226 c and 228 c, comparator230 c and control logic block 234 c, may be used with regard to thein-phase signal path of the baseband processing block 200 c.

In one embodiment of the invention, for DVB-T applications, for example,an on-chip auto-calibration loop may be activated within the basebandprocessing block 200 c upon power-up. The auto-calibration loop mayadjust the cut-off frequency f0 of the filter response of basebandfilters 210 c and 212 c to a value from about 2 MHz to about 5 MHz, forexample. In this regard, the baseband processing block 200 c may supporta plurality of channel bandwidths of 5-8 MHz, such as bandwidthsspecified by the DVB-T standard.

FIG. 2D is a flow diagram illustrating exemplary steps in the operationof a filter supporting auto-calibration mode, in accordance with anembodiment of the invention. Referring to FIGS. 2C and 2D, at 202 d, afrequency response signal of the filter 212 c may be determined using areference frequency signal generated by the reference frequency signalgenerator 222 c. At 204 d, the amplifier 224 c may generate anattenuated reference frequency signal. The comparator 230 c may comparethe frequency response signal generated by the filter 212 c and theattenuated reference frequency signal. At 208 d, the control logic block234 c may generate a control signal 236 c based on the comparison of thefrequency response signal generated by the filter 212 c and theattenuated reference frequency signal. At 210 d, the bandwidth of thefilter 212 c may be adjusted using the generated control signal 236 c.

It should be recognized that although a single-chip dual-band RFreceiver is illustrated, for example in FIG. 1C, the invention is notlimited in this regard. Accordingly, the principles disclosed may beapplied to a single-chip n-band RF receiver, where n is greater than 2.For example, coverage for a third band may be provided utilizing asingle-chip tri-band RF receiver. Furthermore, coverage for a fourthband may be provided utilizing a single-chip quad-band RF receiver, andso on.

Accordingly, aspects of the invention may be realized in hardware,software, firmware and/or a combination thereof. The invention may berealized in a centralized fashion in at least one computer system or ina distributed fashion where different elements are spread across severalinterconnected computer systems. Any kind of computer system or otherapparatus adapted for carrying out the methods described herein issuited. A typical combination of hardware, software and firmware may bea general-purpose computer system with a computer program that, whenbeing loaded and executed, controls the computer system such that itcarries out the methods described herein.

One embodiment of the present invention may be implemented as a boardlevel product, as a single chip, application specific integrated circuit(ASIC), or with varying levels integrated on a single chip with otherportions of the system as separate components. The degree of integrationof the system will primarily be determined by speed and costconsiderations. Because of the sophisticated nature of modernprocessors, it is possible to utilize a commercially availableprocessor, which may be implemented external to an ASIC implementationof the present system. Alternatively, if the processor is available asan ASIC core or logic block, then the commercially available processormay be implemented as part of an ASIC device with various functionsimplemented as firmware.

While the invention has been described with reference to certainembodiments, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted withoutdeparting from the scope of the present invention. In addition, manymodifications may be made to adapt a particular situation or material tothe teachings of the present invention without departing from its scope.Therefore, it is intended that the present invention not be limited tothe particular embodiments disclosed, but that the present inventionwill include all embodiments falling within the scope of the appendedclaims.

1-27. (canceled)
 28. A method for processing wireless information, themethod comprising: performing by one or more circuits within asingle-chip multi-band RF receiver, said one or more circuits comprisinga filter: generating at least one control signal based on a signalstrength of a baseband frequency signal generated by said one or morecircuits within said single-chip multi-band RF receiver; adjusting abandwidth of said filter using said generated at least one controlsignal; filtering said generated baseband frequency signal utilizingsaid bandwidth adjusted filter; and determining a frequency responsesignal of said filter using a reference frequency signal.
 29. The methodaccording to claim 28, comprising generating an attenuated referencefrequency signal by attenuating said reference frequency signal.
 30. Themethod according to claim 29, comprising comparing said attenuatedreference frequency signal with said frequency response signal.
 31. Themethod according to claim 30, comprising generating said at least onecontrol signal based on said comparison.
 32. The method according toclaim 30, comprising averaging said attenuated reference frequencysignal and said frequency response signal prior to said comparing.
 33. Asystem for processing wireless information, the system comprising: oneor more circuits in a single-chip multi-band radio frequency (RF)receiver, said one or one circuits comprising a filter, wherein said oneor more circuits are operable to: generate at least one control signalbased on a signal strength of a baseband frequency signal generated bysaid one or more circuits within said single-chip multi-band RFreceiver; adjust a bandwidth of a filter utilizing said generated atleast one control signal; filter said generated baseband frequencysignal utilizing said bandwidth adjusted filter; and determine afrequency response signal of said filter utilizing a reference frequencysignal.
 34. The system according to claim 33, wherein said one or morecircuits are operable to generate an attenuated reference frequencysignal by attenuating said reference frequency signal.
 35. The systemaccording to claim 34, wherein said one or more circuits are operable tocompare said attenuated reference frequency signal with said frequencyresponse signal.
 36. The system according to claim 35, wherein said oneor more circuits are operable to generate said at least one controlsignal based on said comparison.
 37. The system according to claim 35,wherein said one or more circuits are operable to average saidattenuated reference frequency signal and said frequency response signalprior to said comparing.
 38. A method for processing wirelessinformation, the method comprising: performing by one or more circuitsin a single-chip multi-band RF receiver, wherein said one or morecircuits comprise a filter: generating a baseband frequency signal;generating at least one control signal based on a signal strength ofsaid generated baseband frequency signal; adjusting a bandwidth of afilter using said generated at least one control signal; and filteringsaid generated baseband frequency signal utilizing said bandwidthadjusted filter.
 39. The method according to claim 38, comprisinggenerating a reference frequency signal within said single-chipmulti-band RF receiver.
 40. The method according to claim 39, comprisingdetermining a frequency response signal of said filter utilizing saidgenerated reference frequency signal.
 41. The method according to claim40, comprising attenuating said generated reference frequency signal togenerate an attenuated reference frequency signal.
 42. The methodaccording to claim 41, comprising comparing said attenuated referencefrequency signal with said frequency response signal.
 43. The methodaccording to claim 42, comprising generating said at least one controlsignal based on said comparison.
 44. The method according to claim 42,comprising averaging said attenuated reference frequency signal and saidfrequency response signal prior to said comparison.
 45. The methodaccording to claim 38, wherein said filter comprises a low-pass filter.46. The method according to claim 45, wherein said low-pass filtercomprises a Chebyschev filter.
 47. The method according to claim 38,comprising adjusting a capacitance of said filter based on saidgenerated at least one control signal.
 48. The method according to claim38, comprising adjusting a cut-off frequency of said filter utilizingsaid generated at least one control signal.
 49. The method according toclaim 48, comprising adjusting said cut-off frequency of said filterwithin a range of about 2 MHz to about 5 MHz.
 50. A system forprocessing wireless information, the system comprising: one or morecircuits in a single-chip multi-band RF receiver, wherein said one ormore circuits comprise a filter, said one or more circuits beingoperable to: generate a baseband frequency signal; generate at least onecontrol signal based on a signal strength of said generated basebandfrequency signal; adjust a bandwidth of a filter using said generated atleast one control signal; and filter said generated baseband frequencysignal utilizing said bandwidth adjusted filter.
 51. The systemaccording to claim 50, wherein said one or more circuits are operable togenerate a reference frequency signal within said single-chip multi-bandRF receiver.
 52. The system according to claim 51, wherein one or morecircuits are operable to determine a frequency response signal of saidfilter utilizing said generated reference frequency signal.
 53. Thesystem according to claim 51, wherein one or more circuits are operableto attenuate said generated reference frequency signal to generate anattenuated reference frequency signal.
 54. The system according to claim53, wherein one or more circuits are operable to compare said attenuatedreference frequency signal with said frequency response signal.
 55. Thesystem according to claim 54, wherein one or more circuits are operableto generate said at least one control signal based on said comparison.56. The system according to claim 54, wherein one or more circuits areoperable to average said attenuated reference frequency signal and saidfrequency response signal prior to said comparison.
 57. The systemaccording to claim 50, wherein said filter comprises a low-pass filter.58. The system according to claim 57, wherein said low-pass filtercomprises a Chebyschev filter.
 59. The system according to claim 50,wherein one or more circuits are operable to adjust a capacitance ofsaid filter based on said generated at least one control signal.
 60. Thesystem according to claim 50, wherein one or more circuits are operableto adjust a cut-off frequency of said filter utilizing said generated atleast one control signal,
 61. The system according to claim 60, whereinone or more circuits are operable to adjust said cut-off frequency ofsaid filter within a range of about 2 MHz to about 5 MHz.